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Cannon #2 - The Challenger

A place to ask general spud cannon related questions.
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Cannon #2 - The Challenger

Unread postAuthor: PCGUY » Wed Sep 02, 2009 10:48 pm

Cannon #2

The Challenger

Final Judges Score Chart
-Idea 12/20
-Use of materials 4.7/5
-Creativeness 6.6/10
-Quality of build 4.1/5
-Function 9.1/10

This cannon is part of the SpudFiles Innovative Contest. For details see here...
http://www.spudfiles.com/forums/spudfil ... 19233.html

--Details and pictures from cannon builder--


-Barrel length: 1.0m
-Barrel diameter: 8.0mm hydraulic steel pipe
-Ammo: 8mm (7.96mm) steel bearings
-Mag capacity: 13 rounds

-Release valve: QEV
-Pilot valve: ported blow gun
-Fill Valve: ball valve

-Chamber volume: ~0.2liter
-Pressure: 14bar(203psi)
-Pressure source: bike pump

-Velocity: 220m/s = 50 joule of kinetic energy (at 14bar(203psi))
-Optics: Bushnell Trophy 3-9x40 (red/green sight)
-Other: Adjustable Bi-pod

This is The Challenger, my contribution to this contest. Built on a basic QEV concept, with a couple of add-ons. The parts are self-supporting with a steel frame made of square piping in the middle. A wood stock makes it comfortable to shoot with. The bi-pods are fold-able and the pipe can be detached to make it easy to move. It’s fairly lightweight considering the size of the gun. Shooting from standing position is possible even though I prefer to lie down.

The whole assembly, except for the bi-pods and sight, are hand crafted. I’ve used simple tools as hacksaw, knife and power drill, But for the gun support and other complex parts I’ve used heavy machinery such as lathe and mill. I've put very many working hours into this project which I hope you’ll notice and enjoy!

Special features

On board Chronograph

The chronograph started as a side project were I first had to learn how to program a microcomputer and having it perform the task of reading sensors and present the info on a display. It ended up being an on board velocity measuring unit. The limitation of the speed measure is not yet known but the microprocessor can measure microseconds (0.000001 seconds) and should do the Ir sensor the weakest link. The Ir sensor itself needs 15microseconds to register a bullet. So with 8mm ammo the highest theoretical speed would be 533m/s (1748 fps).

This is a really handy tool when it comes to developing the gun and to actually see the changes of an improvement is great. The sensor unit mounted on the silencer is in the final prototype stage and will very soon be replaced by a better looking one. I might also add some more functions such as shoot counter, Highest/Averaging-value, presenting fps at the same time.

Loading, safety and bullet holder
The ball valve mounted in front of the QEV is used for three purposes. The first is to load a single bullet at the time from the 13 round magazine. The second is that in closed position, it completely blocks the barrel, to prevent the gun from going of in the wrong time. The third function of the valve is to let pressure build up behind the bullet, before the bullet enters the barrel. This is caused by small tolerances in the custom bullet holder, housed inside the steel ball of the valve. While turning the ball valve from closed to firing position, the bullet is forced into place in the holder. This also makes it possible to aim at any height, without have the bullet dropping out of the barrel.

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The chronograph, some bullets and a homebuilt laser calibrator to set the optics right.
The first and only try at 14bar(203psi)
Silencer close up.jpg
Chrono on bordo.jpg
Testing chronograph for the first time
Side View.jpg
Last edited by PCGUY on Fri Apr 16, 2010 1:08 am, edited 4 times in total.
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Unread postAuthor: Hubb » Thu Sep 03, 2009 8:33 am

Idea - 8
Other than the on-board chronograph and maybe the detent system, I see nothing new on this launcher.

Use of Materials - 5
Although there are really no new concepts to this launcher, the materials used are different.

Creativeness - 1
Again, there are really no new features added.

Quality of Build - 5
I really like rifle configurations and this is no different. In fact, it is a very beautiful piece. Also considering the builder used no special tools for construction, this is one fine piece of work.

Function - 10
The launcher appears to function as intended.
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Unread postAuthor: jrrdw » Thu Sep 03, 2009 7:53 pm

Idea: 15 on board crony works for me.

Use of materials: 5 it's put together well.

Creativeness: 8 the on board crony don't make the entire cannon.

Quality of build: 5 it is put together nicely.

Function: 10 it works good hit the target from a good distance.
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Unread postAuthor: MrCrowley » Thu Sep 03, 2009 8:40 pm

Idea: 12
Great idea with the on board chrony, loading system is a nice touch.

Use of materials: 5
Good mix between the metal and the wood, makes the launcher look even better. Well thought out and designed when it came to using these materials.

Creativeness: 6
The chrony is a great touch but it hardly has anything to do with the performance of the launcher and could've been made as a seperate item.

Quality of build: 5
Looks pretty good to me

Function: 10
Chrony works well, launcher works well.
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Unread postAuthor: starman » Thu Sep 03, 2009 9:16 pm

Score Chart

-Idea (20 pts max) 11 - Fairly standard cannon design. Microcontroller builder programmed and usage gets extra bonus points
-Use of materials (5 pts max) 5
-Creativeness (10 pts max) 6
-Quality of build (5 pts max) 5
-Function (10 pts max) 10 Everything seemed to work just as advertised...nothing awkward or out of place stood out.
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Unread postAuthor: clide » Fri Sep 04, 2009 12:13 pm

-Idea (20 pts max) 12
Cannon itself isn't very inventive, but the idea and implementation of the on-board chrony is excellent.

-Use of materials (5 pts max) 4
Being a little picky (that's my job though right?) but the chamber and fittings seem inconsistent with the rest of the gun.

-Creativeness (10 pts max) 6
Again the on-board crony earns it some points

-Quality of build (5 pts max) 5
Well made.

-Function (10 pts max) 9
Seems to work as advertised, but we never saw an overview a clip of a start to finish firing procedure. I think there are a few things that could be improved such as the filling setup.

Edit: Bumped creativity and idea up a point for the nice spring fed magazine
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Unread postAuthor: jackssmirkingrevenge » Fri Sep 04, 2009 11:04 pm

-Idea (20 pts max) - 18
-Use of materials (5 pts max) - 5
-Creativeness (10 pts max) - 8
-Quality of build (5 pts max) - 4
-Function (10 pts max) - 9
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Unread postAuthor: CS » Sat Sep 05, 2009 4:02 pm

Idea - 10 - Would love to see more electronics rat nesting themselves from concept. Does seem there was more to be had though.

Use of materials - 4 - Only because the stock was quick work.

Creativeness - 10 - Like the one off feel to it all. Chrono screen adds a cool element. Only next a range finder/ scope that adjusts for drop in trajectory. Or a circular laser that is fitted around the barrel that would project an approximate area for common bullet spread, also accounting for trajectory and distance. What can I say? Electronics with guns :-)

Quality of build - 4

Function - 8 - Replicating a rifle design, but not noting accuracy kind of leaves me hanging. Looks functionable?
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Unread postAuthor: jagerbond » Wed Sep 09, 2009 2:15 am

-Idea 10
-Use of materials 5
-Creativeness 9
-Quality of build 4
-Function 9
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Unread postAuthor: sgort87 » Fri Sep 11, 2009 4:52 pm

Idea: 12
Pretty good design with the loading system and chrony.

Use of Materials: 5
Very nice job finding parts to work well with each other. It looks and operates amazingly. I love the wood/metal look of the chrony box. Is that a drywall screw on the left side of the gun though?

Creativeness: 6
Nice launcher, but not too much creativity used.

Quality of Build: 5

Function: 7
The only thing I got against it is that the bike pump totally puts a downer on this gun. The time and effort it takes to reload is my biggest consideration when judging function. If it used 3.5 oz CO2 tanks, you'd totally be getting a 10.
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Unread postAuthor: inonickname » Sat Sep 12, 2009 10:14 pm

-Idea: 10; The loading system is good, onboard chronograph is nice but in reality most have this has been done.

-Use of materials: 4.5; It's all rounded out nicely into a very smooth and complete package. Perhaps the stock could have been rounded out a little more.

-Creativeness: 7; the onboard chonograph and other features are excellent.

-Quality of build: 4.5; neat, tidy, done perfectly. As I said the stock could use more rounding out but it's a very nice, complete package.

-Function: 9; could be improved with an onboard HPA system, onboard pump or CO2 tank. But that's a personal preference really. The chronies proximity to the muzzle may give overly generous readings.
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Unread postAuthor: Carlman » Sat Sep 12, 2009 10:46 pm

-Idea: 5 - Harsh? maybe. Id rather have an external chrono that can be used for multiple guns. Rest is pretty standard.

-Use of materials: 4 - Yea, some more attention spent on the stock and shed score higher in my books.

-Creativeness: 3 - Chrono doesnt get it there itself

-Quality of build: 4.5 - looks just fine.

-Function: 8 - Seems to work well
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Unread postAuthor: THUNDERLORD » Sun Sep 13, 2009 6:14 pm

Man this one looks very nicely built!!!
And good shooter.
Safety incorporated in design is innovative itself! 8)
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